1. Field of the Disclosure
The present disclosure relates to noninvasive optical sensors capable of detecting light attenuated by body tissue. More specifically, the disclosure relates to the combination of reusable and disposable components of such sensors.
2. Description of the Related Art
Early detection of low blood oxygen is important in a wide range of applications, including patient monitoring, the fitness industry, home care and the like. Noninvasive oximetry was developed to study and to measure, among other things, the oxygen status of blood. Pulse oximetry—a noninvasive, widely accepted form of oximetry—relies on a sensor attached externally to a patient to output signals indicative of various physiological parameters, such as a patient's blood oxygen saturation.
A pulse oximeter sensor generally includes one or more energy emission devices, such as specific wavelength emitting LEDs, and one or more energy detection devices. The sensor is generally attached to a measurement site such as a patient's finger, ear, ankle, or the like, using an attachment mechanism such as a disposable tape, reusable housing, a plastic or hook-and-loop fastening strap, or the like. The attachment mechanism positions the emitters and detector proximal to the measurement site such that the emitters project energy into the blood vessels and capillaries of the measurement site, which in turn attenuate the energy. The detector then detects that attenuated energy. The detector communicates at least one signal indicative of the detected attenuated energy to a signal processing device such as an oximeter. The oximeter generally calculates, among other things, one or more physiological parameters of the measurement site.
Noninvasive oximetry sensors can be disposable, reusable, or some combination thereof. Reusable sensors offer advantages of superior cost savings. However, reusable sensors are often available in a limited number of sizes even though patient measurement sites, such as fingers or toes, can have a much larger size distribution. Therefore, sometimes reusable sensors do not readily conform to each patient's measurement site. Disposable sensors on the other hand offer superior conformance to the measurement area. However, disposable sensors are generally more costly due to limited use of the relatively expensive sensor components which could otherwise last for repeated uses.
Faced with the drawbacks of reusable and disposable sensors, manufacturers began designing a number of middle-ground sensors. For example, some manufacturers offer a reusable detector portion that couples to a disposable emitter portion. After a single use, the disposable emitter portion is detached from the reusable detector portion and discarded. While this design reuses some of the expensive electronic components, obviously others are still discarded.
Another example of a middle-ground sensor includes a reusable “Y” type sensor, where a reusable emitter portion connects to one branch of the “Y” while a reusable detector portion connects to the other branch. A disposable tape positions the two branches on a measurement site. In this design, the electronics are reusable; however, the multiple wires tend to be somewhat difficult to properly attach, especially with a moving patient.
Other examples of middle-ground sensors include a disposable tape sandwich where a reusable flexible circuit housing an emitter portion and a detector portion, are “sandwiched” between adhesive layers. Separation of such disposable tape sandwiches can be cumbersome. In yet another example of a middle-ground sensor, the Assignee of the present application disclosed a reusable flexible circuit that is snapped into a disposable tape. In an embodiment of that disclosure, small pegs on the flexible circuit snap into mechanically mating elements on the disposable tape. Grooves allow some longitudinal travel between the reusable portion and the disposable portion, thereby allowing for some self adjustment between components to account for differences in radial attachment requirements.